Pattern Breakdown
Understanding the regex pattern ^(0[1-9]|1[0-2])/(0[1-9]|[12][0-9]|3[01])/\d{4}$:
- ^ - Start of string
- $ - End of string
- \d - Any digit (0-9)
- [...] - Character class
- (...) - Capturing group
- {n,m} - Quantifier (n to m times)
- | - Alternation (OR)
Examples
| Input | Result | Explanation |
|---|---|---|
01/15/2024 |
✓ Match | Valid US date |
12/31/2024 |
✓ Match | End of year |
13/01/2024 |
✗ No Match | Invalid month |
Code Examples
JavaScript
JavaScript
const pattern = /^(0[1-9]|1[0-2])\/(0[1-9]|[12][0-9]|3[01])\/\d{4}$/;
const text = "01/15/2024";
// Test if string matches
if (pattern.test(text)) {
console.log("Valid!");
}
// Extract matches
const matches = text.match(pattern);
console.log(matches);
Python
Python
import re
pattern = r'^(0[1-9]|1[0-2])/(0[1-9]|[12][0-9]|3[01])/\d{4}$'
text = "01/15/2024"
# Test if string matches
if re.match(pattern, text):
print("Valid!")
# Find all matches
matches = re.findall(pattern, text)
print(matches)
PHP
PHP
<?php
$pattern = '/^(0[1-9]|1[0-2])\/(0[1-9]|[12][0-9]|3[01])\/\d{4}$/';
$text = "01/15/2024";
// Test if string matches
if (preg_match($pattern, $text)) {
echo "Valid!";
}
// Find all matches
preg_match_all($pattern, $text, $matches);
print_r($matches);
?>
Java
Java
import java.util.regex.*;
String pattern = "^(0[1-9]|1[0-2])/(0[1-9]|[12][0-9]|3[01])/\\d{4}$";
String text = "01/15/2024";
Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(text);
if (m.matches()) {
System.out.println("Valid!");
}
Use Cases
Common applications: US applications, legacy systems, user input
- Form validation and input sanitization
- Data extraction and parsing
- Search and replace operations
- API request/response validation
- Log file analysis
Frequently Asked Questions
What is the regex pattern for us date format regex?
The regex pattern is: ^(0[1-9]|1[0-2])/(0[1-9]|[12][0-9]|3[01])/\d{4}$. Match US date format MM/DD/YYYY with basic validation for month and day ranges.
How do I use the us date format regex pattern in JavaScript?
In JavaScript: const regex = new RegExp('^(0[1-9]|1[0-2])/(0[1-9]|[12][0-9]|3[01])/\\d{4}$'); or const regex = /^(0[1-9]|1[0-2])\/(0[1-9]|[12][0-9]|3[01])\/\d{4}$/;
Does this pattern work in Python?
Yes, use: import re; pattern = re.compile(r'^(0[1-9]|1[0-2])/(0[1-9]|[12][0-9]|3[01])/\d{4}$') in Python. Most regex patterns are cross-language compatible.
What are common use cases for us date format regex?
US applications, legacy systems, user input
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